The present invention relates to a liquid crystal display device and more particularly to the disposition of columnar spacers which hold a constant space between a first substrate and a second substrate which are provided in the liquid crystal display device.
At the present time, many liquid crystal display devices which are generally used are each composed of a pair of substrates (for example, glass substrates) and a liquid crystal composition which is encapsulated in a space defined between the pair of substrates. Specifically, for example, in the case of a liquid crystal display device using an In-Plane-Switching (IPS) system, thin film transistors each having a semiconductor layer made of amorphous silicon or the like, pixel electrodes, signal lines, gate electrodes, a counter electrode, and the like are formed on one substrate (hereinafter referred to as “a TFT substrate”). In addition, a light blocking film, color filters, and the like are formed on the other substrate (hereinafter referred to as “a CF substrate”). Also, the TFT substrate and the CF substrate are disposed so as to face each other with a constant space being held by spacers, and are sealed in peripheries thereof with a sealing agent. Also, a liquid crystal composition is encapsulated in the space between the TFT substrate and the CF substrate, thereby constructing the liquid crystal display device.
As far as the spacer concerned for holding the constant space, instead of using plastic beads whose particle diameters are uniform and which are used in the manner of being uniformly sparged on the substrate, in recent years, columnar spacers which are structured by directly forming a pattern on a non-display area of the CF substrate have been frequently used.
As the columnar spacer, there are known two spacers: a main columnar spacer; and a sub columnar spacer. The main columnar spacer serves to steadily support the gap space defined between the TFT substrate and the CF substrate. Also, the sub columnar spacer serves to support the gap space defined between the TFT substrate and the CF substrate only when a pressure is applied between the TFT substrate and the CF substrate. This technique, for example, is disclosed in JP-2005-338770-A.